Detection and identitication of human type A influenza viruses by the reverse transcriptase-polymerase chain reaction in Bulgaria

Introcludon/Purpose: Reverse transcriptase-polymerase chain reaction (RT-PCR) for detection, typing, and subtyping of the hemagglutinin and neuraminidase genes of influenza type A (H3N2 and H1N1) viruses in patients' specimens has been developed and applied for the purpose of influenza virological surveillance in the 2003/2004 and 2004/2005 winter seasons. The technique was performed prior to the viral isolation, in order to determine the influenza outbreaks' etiological agent. Methods: During the 2003/2004 season, RTPCR was performed following an initial screening of 50 patients' samples by 3 other methods. In the 2004/2005 season, the method was used for direct identification of 77 clinical samples. Results/Discussion: All the samples tested were taken during the peak of influenza outbreaks. The report presented is the first one for the country to demonstrate an RT-PCR effective application in influenza virus detection in clinical samples from epidemic outbreaks.